优先队列，，没什么好说的。
#include<iostream>#include<queue>#include<functional>#include<iomanip>using namespace std;//n is the people's num,and k is the num of roomint n, k;priority_queue<double,vector<double>, greater<double> > input,ans;int main(){while (cin >> n >> k){double in,sum=0;for (int i = 0; i < n; i++){cin >> in;input.push(in);}for (int i = 0; i < k; i++){in = input.top();sum += in;ans.push(in);input.pop();}while(!input.empty()){in= ans.top()+input.top();sum += in;input.pop();ans.pop();ans.push(in);}cout << fixed << setprecision(3) << sum / n << endl;}return 0;}
这里的风景美不胜收，真让人流连忘返。
